The present disclosure relates to an electric fastener driving tool driven by a motor.
As a fastener driving tool for driving a pin or a staple into a wooden material or a gypsum board, a tool is known that is configured to move an impact driver against a biasing force of an impact spring and then release the impact spring to perform driving.
This type of fastener driving tool is provided with a plunger that can reciprocate along a driving direction and is biased in the driving direction by the impact spring. The impact driver is fixed to the plunger.
Usually, the plunger is stopped at a position away from bottom dead center at which a driving target (pin, staple, etc.) is driven by the impact driver. When a driving command is input, the plunger is moved in a direction opposite to bottom dead center via a motor and a drive mechanism having an anti reverse rotation function.
When the plunger reaches top dead center that is farthest from bottom dead center, the plunger and the drive mechanism are disengaged from each other. The plunger (and the impact driver) is instantaneously moved toward bottom dead center by the biasing force of the spring, and the driving target is driven into a substrate (wooden material, gypsum board, etc.).
The driving operation as such is achieved by driving the motor. The plunger is stopped at a position away from bottom dead center in each cycle of driving operation.
In order to stop the plunger at a desired stop position, it has been proposed to detect that the plunger has reached top dead center after power supply to the motor is started, and then to supply power to the motor for a certain period of time (see, for example, Japanese Examined Utility Model Application Publication No. H07-33575).
For the same purpose, it has also been proposed to measure time until the plunger reaches top dead center after power supply to the motor is started, and set power supply time of the motor to follow based on the measured time (for example, see Japanese Patent No. 5424105).